Potential Group Purchase - Wiseco GS650 741cc pistons

[Chuck78]

FYI here are a few photos of crankcase clearancing. A cheap air powered die grinder and a refurbished $15 or $20 cylindrical/rounded end carbide burr bit really mase efficient work of the light material removal needed.




Also I theorize than 1981-1982 GS550 crankcases may not even need this clearancing, as aside from the 5 speed vs 6 speed transmission and lack of kickstarter mechanism parts and kicker shaft hole in clutch cover, the 1981 GS650E shares the same part numbers listed for all other GS550 bottom end parts - crank, crankcases, etc.
Not sure where thedeck heiggt difference comes into play, the rods? different cylinder height? Different head or base gasket on the 650E vs 650G? Bases are definitely different as the E is roller bearing bottom with the egg shaped o-rings and unrestricted oil flow, G is high oil pressure low volume plain bearing bottom with an oil jet squirter to build more pressure in the crank bearings due to the nature of plain/babbit style bearings.

[Chuck78]

I have a pair of 550's that I'd like to build for me and the mrs, but I don't want to start ripping them apart if it's not doable. The pistons seem like the right call. Also, does anyone have a good starting point for where to get the pistons made, what I need to bore the cylinders at, really, what I need to do to make this happen? If you've got a starting point, I can read from there.

As mentioned by himself, Tom aka tadakan is looking to do the same with Wiseco's, & 2 or 3 other members have shown interest within the past year in other threads in this forum,you may want to reach out to them to see if they are able to go in on the purchase to get the price down further:

LeanMeanGsMachine

https://www.thegsresources.com/_forum/member.php?44995-LeanMeanGsMachine

JeremiG2001

https://www.thegsresources.com/_forum/member.php?47961-JeremiG2001

[Guest]

Hi,
I'm in need of oversize pistons for a GS650G and somebody redirected me to this topic.

If I read this correct, I need to find 2 more people to order a set from Wiseco and it would cost around ~USD500 per person?
These pistons would actually be 1.5mm oversize and would also increase the displacement to 741ccm?

How different are they from the CruzinImage BigBore Kit?

Thanks for your help!

[tadakan]

Hi Berti,

Myself and at least one other member have talked a bit about another purchase. He was looking at two sets, so we probably have enough for an order. It just hasn't been priority for either of us.

I can't speak to wiseco vs the kit you mention other than to say that wiseco is a really respected name in the business. I think someone may have mentioned these pistons were a yoshimura design? Not sure. I would expect them to be about the best that you can get for the 650 cylinders.

There's also info about getting headgaskets made in the thread. I bought a multilayer steel gasket when folks did a group buy, but there's also an option for another type that's cheaper and doesnt have a minimum.

Also, i'm just down in Olympia, WA so we're practically neighbors. Vancouver is a beautiful city.

Tom

[Old Colt]

Hi,
I'm in need of oversize pistons for a GS650G and somebody redirected me to this topic.

If I read this correct, I need to find 2 more people to order a set from Wiseco and it would cost around ~USD500 per person?
These pistons would actually be 1.5mm oversize and would also increase the displacement to 741ccm?

How different are they from the CruzinImage BigBore Kit?

Thanks for your help!

I would expect at the price of that kit those would be cast pistons. The fact the kit comes with a head gasket makes it an easy job.
If you essentially just cruise with your bike they should be fine but I would caution they have a generous dome which will give you a rather high compression. That might crimp your style from what you are used to and require more setup work with the carbs and ignition. Something all of us need to deal with setting up the Wisecos.

Depending on the quality of the pistons they might possibly have some reliability if you twist up the revs or do get into much detonation should a load of gas not be up to snuff.
I could not find any pictures with a side view to see what construction design is used at the oil control ring, as in drilled or slotted relief behind the ring. This makes a difference in durability.

The Wiseco route, they will stand up to a poorly tuned engine while you get the bike running.
They are a top quality forged piston, very well machined and will not break.
You need a headgasket, they are available overseas, I do not recall if the contact info to buy them is in this thread.
The higher price provides you with a better than factory build.

I would not expect the $170 USD kit is equal to the original parts.

[Guest]

Hi Berti,

Myself and at least one other member have talked a bit about another purchase. He was looking at two sets, so we probably have enough for an order. It just hasn't been priority for either of us.

I can't speak to wiseco vs the kit you mention other than to say that wiseco is a really respected name in the business. I think someone may have mentioned these pistons were a yoshimura design? Not sure. I would expect them to be about the best that you can get for the 650 cylinders.

There's also info about getting headgaskets made in the thread. I bought a multilayer steel gasket when folks did a group buy, but there's also an option for another type that's cheaper and doesnt have a minimum.

Also, i'm just down in Olympia, WA so we're practically neighbors. Vancouver is a beautiful city.

Tom

Hello Neighbour,
Thanks for letting me know. I know I won't get my bike anymore on the road this year, but I would rather finish that whole engine disaster sooner than later. That said, maybe someone has a spare set sitting at home and wants to part with it?!

I would expect at the price of that kit those would be cast pistons. The fact the kit comes with a head gasket makes it an easy job.
If you essentially just cruise with your bike they should be fine but I would caution they have a generous dome which will give you a rather high compression. That might crimp your style from what you are used to and require more setup work with the carbs and ignition. Something all of us need to deal with setting up the Wisecos.

Depending on the quality of the pistons they might possibly have some reliability if you twist up the revs or do get into much detonation should a load of gas not be up to snuff.
I could not find any pictures with a side view to see what construction design is used at the oil control ring, as in drilled or slotted relief behind the ring. This makes a difference in durability.

The Wiseco route, they will stand up to a poorly tuned engine while you get the bike running.
They are a top quality forged piston, very well machined and will not break.
You need a headgasket, they are available overseas, I do not recall if the contact info to buy them is in this thread.
The higher price provides you with a better than factory build.

I would not expect the $170 USD kit is equal to the original parts.

Thanks for your input. I have already the whole engine apart and I'm aware of all the additional tweaks and tuning, as I'm not going with stock intake and exhaust. Also the big bore kit (wether wiseco or cruzin image) needs a lot of carb testing and rejetting anyway.

I'm not going to race with that bike, but I do like to ride a bit more "sporty"... That said - 3 cruzin sets come for the price of one wiseco.

[prichmon]

Hello all;

I am starting the process of my 550/650 build. I have a few questions which I was not positive the answer from my search.

1978 GS550 wire wheel.
1981 GS650E

Can I run the VM22s from the 550?
Will the CVs bolt to the airbox of the 550?
What is the suggested starting point for the jetting with the 650 and VM22?
Compression is 150-160psi. What is the stock compression?
If I bought the 740 kit what is the starting point for jetting with the vm22s?
Would larger VMs work from a 750 or larger?

Could someone confirm I can run either of the head pipes and cans?
Does the final drive need changed to better suit the bike?
What are thoughts on doing a smaller more modern chain?
What are the advantages of the aluminum 1100 swingarm? Weight saving only?

I scalped the front end, dual disc setup from the 650E
I have a RZR V/R to go in while the bike is down. I can't remember for the life of me the name and P/n right now.
The foot pegs look like they would bolt up but the pegs would be at the wrong angle. Any idea on rubber mounted pegs which will bolt up?

I'm sure Ill have more questions.

Thanks for the help.

Rich

[Guest]

Another possible Wiseco order?

Looks like a cpl more people are interested in another order from Wiseco for the 741cc pistons.

Let's see who is interested and if we can pull off another group purchase to bring costs down for everyone!

So far I have seen interest by:
@tadakan
@Berti
@BigWookie
@MechMessiah
@EGB

Not sure, if these people get automatically notified by the forum. I will send individual messages to them.

And to all the people that got pistons in the first group buy - has anybody completed their build by now and could give feedback on performance/durability?
What other modifications are needed? Sure bigger pistons need bored cylinders. The 550/650 conversion people need also a different base gasket. The 650 people can use standard base gaskets?
Also, carbs obviously need rejetting. But are the standard size carbs enough, or are bigger carbs needed as well?

AAANNNNDDDD the biggest question - what's the final output on the rearwheel??? Anybody done some dyno runs??

[tadakan]

@Berti

I'm definitely still interested. I have donor 550 and 650 engines and mls baskets. If you have the energy to organize the piston order, let me know.

Also, definitely interested in hearing about peoples' progress and learning experiences. I've heard some stuff about needing to add an oil cooler.

[MechMessiah]

Hi all, I'm definitely up for this. I wanna do the 550/650 build I keep reading about.

[Guest]

Soooo. Updates:

I just talked to Wiseco. They still have the files from the last purchase, BUT I can't order them. They don't sell custom orders to other people. So I either have to get permission from whoever bought it in the first place or make changes to the plans so it becomes a different custom order.

I sent Andy (Ace07) already a message a while ago with no response. Looks like he has been off this forum for a while now.
Does anyone have any additional options to contact him? That would be much appreciated as I would like to skip the hassle of 'redesigning' the pistons.

[Guest]

I have things sorted out!

The short version:
Same pistons as before. Set consists of pistons, rings, clips, pin. All you need.

First 3 sets are $472 each.
6 sets will be $392 each.
9 sets would $364 each.

Shipping is extra.

Who would be interested?

[Chuck78]

I've got several from the first batch (for my 2 projects + spares for me in the future) including one that I was hoping to have fired up by now (major personal injuries/surgeries and too many projects!!!), but I am happy to see the possibility of another batch of these getting made!

I'm not sure why they were so adamant about requiring Andy's permission to make another batch of his "Custom order pistons," perhaps you could have just asked them what Andy asked for us initially - "Dear Wiseco, can you make another batch of 12 or more of your old GS650 Wiseco model K740 pistons? If you look into it, you do still have the old old drawings on file for these, as another associate of ours had you re-make a batch on 2017/2018."

They still wanted to scan Andy's piston and head samples, but they just confirmed that their old drawings were correct with the info from Andy's parts. They may have made some updated CAD file drawings of their new version of the old pistons, but it's still basically the same as the old pistons they offered ages ago.






On a side note, there is a slight chance that in a few years, I may be looking into getting some 58mm (+2mm oversized, with quench area at edge of crown) 10:1 or 10.5:1 compression GS550 hemi pistons made, or even a smaller-than-stock 58mm GS650 piston (with shorter compression height by something like .4mm) to run with a 650 head and 550 cylinder on a 550 bottom in a December 1981 or older GS550 chassis...

Racing my 449cc or 489cc GS425 in WERA Formula 500 and Vintage 3 / Vintage 4 classes will not be terribly competitive except the once-a-year Formula 500 class races at AMA Vintage Motorcycle Days, and a 570cc Suzuki GS550 would be far more competitive in Vintage 4 if I were to get more seriously into WERA racing and wanting to be competitive. There are more WERA races around the Midwest/Ohio than AHRMA. In AHRMA, I'd do great in Vintage Lightweight Superbike at 449cc (470cc class limit), and a modified GS550 (Dynoman makes custom-order 630cc +4mm GS550 hemi pistons!) or GS650 (stock 673cc pistons or +1.0mm OS, 685cc class limit) would do great in middleweight superbike as well...
But for WERA, some custom pistons in a 570cc GS550 or 650 hybrid would be the best ticket for middleweight vintage Suzuki racing...
I'm building the GS425 up for now just to get my feet wet into some track days and vintage racing. the 489cc engine will only qualify for WERA, AHRMA will have to use stock sleeves and GS750 Wiseco K844 pistons for 449cc GS400/425... I have two engines luckily!

So I may (or others may) in the distant future be making some fairly unique custom piston batches. More likely JE Pistons or Carillo Rods / CP pistons unless there was a 12+ batch being needed... a 570cc GS550/GS650 hybrid would be a fantastic combo for the racing regulations or not, and a 570cc high compression hemi head GS550 would also be a quite a nice engine especially if some squish band quench area could be machined into the edges of the piston crown depending on combustion chamber diameter...
This is just a pipedream for now, I have yet to get out on the track on the GS twin yet, but is a possibility for in the future to build something like this...

[tadakan]

I'm interested in one set. Would love it if we got to 6 sets, but I can afford it at 3 sets if I have to.

[Guest]

So, let's start counting:
Berti 1 Set
Tadakan 1 set
Chuck ?possibly?
MechMessiah ?1 Set?

Who else?